feat: add matomo to header in index.html (#3824)

index.html

@@ -19,6 +19,23 @@
     -->
     <link rel="manifest" href="/manifest.json" />
 
+    <!-- Matomo -->
+    <script>
+      var _paq = window._paq = window._paq || [];
+      /* tracker methods like "setCustomDimension" should be called before "trackPageView" */
+      _paq.push(['trackPageView']);
+      _paq.push(['enableLinkTracking']);
+      _paq.push(['setCustomUrl', 'https://beta.explorer.cardano.org/']);
+      (function() {
+        var u="https://cardanofoundation.matomo.cloud/";
+        _paq.push(['setTrackerUrl', u+'matomo.php']);
+        _paq.push(['setSiteId', '8']);
+        var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+        g.async=true; g.src='https://cdn.matomo.cloud/cardanofoundation.matomo.cloud/matomo.js'; s.parentNode.insertBefore(g,s);
+      })();
+    </script>
+    <!-- End Matomo Code -->
+
     <!--
       Notice the use of  in the tags above.
       It will be replaced with the URL of the `public` folder during the build.